Method of forming joint construction of precast concrete columns and beams

ABSTRACT

A construction method of rigid structural joints between precast concrete columns and beams by utilizing two sets of jointing system in combination. In vertical direction columns are jointed by placing steel sleeves within joint panel zone wherein protruding main bars from upper and lower columns are inserted and grouted by non-shrink mortar giving structural continuity. In horizontal direction beams are jointed by formation of U-shaped grooves at beam ends wherein main reinforcing bars are enclosed and lap-jointed to preassembled main bars placed inside of aforesaid grooves by casting concrete within the grooves.

United States Patent. [191 Mikami et al. 1

I111 3,867,805 1 51 Feb. 25, 197.5

[75] Inventors: Yuzo Mikami, Tokyo; Hideyuki Kobayashi, Saitama; TetsuyaSasaki, Tokyo, all of Japan [73] Assignee: Kajima Kensetsu KabushikiKaisha,

Tokyo, Japan 22 Filed: May 18,1973 211 Appl. No.2 361,758

[30] Foreign Application Priority Data May 18, 1972 Japan 47-49467 [52]US. Cl 52/744, 52/252, 52/259, 52/263, 52/726 [51] Int. Cl E04b l/04[58] Field of Search 52/260, 251, 252, 259, 52/263, 250, 432, 253,258,722, 72,6, 744

[56] References Cited UNITED STATES PATENTS 1,516,074 11/1924 Borg52/252 X 2,587,724 3/1952 Henterson 52/253 X 2,618,146 11/1952 Ciarlini52/259 X 3,151,464 10/1964 Sato et a1 52/738 X 3,226,894 1/1966=Buchardt et a1. 52/252 X 3,540,763 11/1970 Yee 287/108 3,552,787 1/19713,562,979 2/1971 l I; n

Yee 52/251 X 3,613,325 10/1971 3,645,056 2/1972 Gerola 52/259 3,691,7109/1972 Gilbert et a1 52/251 3,722,159 3/1973 Kessler 52/260 X FOREIGNPATENTS OR APPLICATIONS 6,409,077 2/1966 Netherlands 52/263 626,0977/1949 Great Britain...' 52/283 1,395,488 3/1965 France 52/432 1,427,03312/1965 France 52/253 564,146 9/1944 Great Britain 52/251 PrimaryExaminerErnest R. Purser Assistant Examiner-Leslie A. Braun Attorney,Agent, or FirmSughrue, Rothwell, Mion, Zinn & Macpeak [57] ABSTRACT Aconstruction method of rigid structural joints between precast concretecolumns and beams by utilizing two sets of jointing system incombination. In vertical direction columns are jointed by placing steelsleeves within joint panel zone wherein protruding main bars from upperand lower columns are inserted and grouted by non-shrink mortar givingstructural continuity. In horizontal direction beams are jointed byformation of U-shaped grooves at beam ends wherein main reinforcing barsare enclosed and lapjointed to preassembled main bars placed inside ofaforesaid grooves by casting Concrete within the grooves.

2 Claims, 19 Drawing Figures PATENTEDFEBZSIQYS SHEET 1 OF 5 FIG. I

FIG. 2

FIG. 3

PATEHTEDFEBZSIBYS SHEET 2 BF 5 FIG. 4

FIG 5 FIG. 6

pmm mwzsms 3,857, 5

saw 3 [1F 5 1 METHOD OF FORMING JOINT CONSTRUCTION OF PRECAST CONCRETECOLUMNS AND BEAMS The present invention is generally concerned withconstruction methods of rigid structural joints between precast columnsand beams in prefabricated building construction, and more particularlyrelates to the use of steel bar splice sleeves at the joint panel zonefor column-to-column joint, and the use of U-shaped beam ends in whichmain bars are cast in and lap-jointed to the pre-assembled bars forbeam-to-beam joint, the use of the two jointing methods being combinedinto one integrated system.

One of the most important questions encountered in the construction ofprefabricated concrete structure of column and beam type is theformation of structural joints between the prefabricated elements.According to the normal practice, for structural reasons such joints aregenerally positioned where the stresses under loads are relativelysmall, i.e., at the mid-span for the beams and mid-storey height for thecolumns, similar to the normal practice in steel frame construction.However, this structural advantage is turned into severe disadvantagesas far as the manufacturing, handling, and site operations of suchelements are concerned, because the elements thus formed generally havehighly complicated three-dimensional forms particularly where the beamsare deployed in two directions for the structural reasons arising fromearthquake resistant design. In addition, such elements become ratherheavy and unstable during erection, thus needing much temporary supportsto be held up safely in position.

Furthermore, the column joint formed at mid-storey height presentsproblems in architectural finishes, as it may easily come close to thelevel of vision of the users or the residents of the building whenoccupied.

Another important questions in the construction of structural joints inprefabricated concrete building is the provision of tolerances and thesimplification of jointing operation. As an inherent nature of concreteconstruction, it is not possible to achieve the accuracy in jointingparts comparable to that of steel frame construction. Therefore, the useof welding and bolting in the jointing operation is not desirable forstructural as well as for economical reasons. On the other hand, if

the jointing operation may be performed only through the grouting andthe concreting operation, utilizing the bonding effect of reinforcingbar to mortar or concrete, it will result in much simplicity andeconomy, and will also provide adequate tolerance necessary for thistype of construction, and at the same time will achieve structuralcontinuity and monolithic character inherent to the reinforced concreteconstruction.

The instant invention has been accomplished while taking theabovementioned technical circumstances into consideration.

A primary object of the invention is to achieve the A further objectofthe invention is to conceal the structural joints which tend to resultin an inferior architectural effect into places where the occupants orthe users of the building may not see easily.

Another significant object of the invention is to achieve fullcontinuity and rigidity of the structural joints at least comparable tothose of normal reinforced concrete construction, wherein the joints aremade monolithic through the utilization of bonding between thereinforcing bars and the concrete.

The objects of the invention are achieved through the provision ofstructural joints in or adjacent to the joint panel zone. Thecolumn-to-column joint is formed by providing steel splice sleeveswithin the joint panel zone, wherein protruding main reinforcing barsfrom upper and lower precast columns are inserted and locked, upon thehardening of non-shrink mortar grouted inside the sleeves, through thebonding and wedging effect of the bars, mortar, and the sleeves whichare slightly tapered towards the top and the bottom of the length. (Areference is made to the U.S. Pat. No. 3,540,763 for the principle ofthe steel splice sleeve). Said bars are of deformed type and theinterior walls of the sleeves are finely grooved.

The beam-to-beam joint is formed through the lapping effect of the beammain bars which are cast within the U-shaped groove at the beam ends andthe preassembled main bars which are projecting from the joint panelzone into the said groove upon the hardening of concrete poured withinthe said groove. The U- shaped groove is given an adequate length toensure full structural continuity between the jointed elements throughthe bonding of said groove, bars, and concrete, further secured by thestirrup bars precast within the U-shaped groove and bent down over thepreassembled bars prior to the concreting. No or little falsework isnecessary for the concreting operation as the said U-shaped grooveitself functions as a formwork. Full sectional area of the joint becomesstructurally effective after the jointing.

BRIEF DESCRIPTION OF THE DRAWINGS DETAILED DESCRIPTION OF THE INVENTIONReferring now to the drawings, there is illustrated, in FIGS. 1 through6, an outline of various embodiments in accordance with this invention.

Basic elements with which the structural joint is formed according tothis invention comprise a precast reinforced concrete column 1, aprecast reinforced concrete beam 2, and a sleeve 3 serving as aconnector .to reinforcing bars projecting from the column.

As shown in FIG. 1, an end portion of a beam 2, which is formed with agroove 4 of a U-shape in section, is positioned on a lower column I. Asleeve 3 is so positioned in a joint panel zone that the opposed openends thereof align with the reinforcing bar of the column. The bar 5extending from an upper end of a lower column 1 is inserted'in thesleeve 3. A set of pre-assembled bars 6 is set in a space formed by thetwo grooves at the ends of right and left beams. Then an upper column 1is so placed on the lower column 1 that the bar 5 extending from thelower end of the upper column 1 is inserted within the sleeve 3,followed by filling the interior of the sleeve with a grouting materialto lock the bars 5 of the upper and lower columns to each other. Saidspace formed by the two grooves and extending across the ends of bothcolumns is filled with concrete to make the columns and beamsmonolithic.

As seen in FIG. 2, a sleeve 3 can also be embedded within a precastconcrete block 7 to be put in position at a joint panel zone, leavingits upper and lower ends open on the surface of the block. The block isprovided with a reinforcing bar 6' extending laterally.

Both upper and lower columns 1 and 1 are jointed together by bars 5, 5by means of the sleeve, in which a grouting material is subsequentlypoured. A beam 2 is made monolithic with respect to the columns byconcrete poured in a groove 4.

FIGS. 3 through 6 show the use ofa sleeve embedded in a central pointalong the length of a beam.

IN FIG. 3 there is shown a sleeve 3 which is embedded in a central pointalong the length of a precast concrete beam 2, leaving upper and loweropenings of the sleeve on the top and bottom surfaces of the beam. Thebeam 2 is formed with a groove 4 of a U-shape in section at one endthereof, and provided with a projecting bar 6' at the other end thereof.One beam 2 is arranged .to the other beam 2 in butt joint or face toface relationship at a middle point along the span between columns l andl, with the setting of the projecting bar 6' in the U-shaped groove 4,and the groove 4 is filled with concrete, to joint the beams 2 and 2 ata middle point between columns.

FIG. 4 shows a manner of jointing wherein a sleeve 3 is embedded in acentral point along the length of a precast beam 2, the beam is formedwith a U-shape groove 4 at both ends thereof. said beam 2 is arranged oncolumn 1 in a butt joint relationship with the other beam at anintermediate point between columns 1 and l, a bar 6 is set in thegroove, and concrete is poured therein.

FIG. 5 shows a manner of jointing wherein a sleeve 3 is embedded in aprecast concrete beam 2 at a portion central along the length thereof,the beam is provided with a U-shape groove or channel at both endsthereof, a precast concrete beam 2' to be used in the intermediate zonebetween columns is provided with a projecting bar 6' at both endsthereof, said bars 6' and 6 are set in the U-shape grooves 4, andconcrete is poured in the grooves.

FIG. 6 shows a case where the outline of framing takes a T-shapeconfiguration by the provision of a wall panel or column 8, the top ofwhich is jointed to the bottom surface of a reinforced concrete beam 2carrying a sleeve 3 embedded therein. The column 8 and beam 2 may bemanufactured separately and assembled in the building site.

FIGS. 7 and 8 show details of a column 1. The column 1 may be eithercircular, square, or cruciform in section, is provided with bars 5projecting from the top and bottom thereof, and is formed with a dent 9and a corresponding projection 10 on the top and the bottom thereof,respectively.

FIGS. 9 and 10 show an example of a precast beam. The beam 2 is formedwith a U-shape groove 4 at the both ends thereof. In some cases, thebeam is provided with a sleeve embedded therein at a portion centralalong the length thereof, and the sleeve is used for jointing a wallpanel or column 8 to the top and/or bottom of the beam 2. A dent 11receives a projection formed on the bottom of a column 8 jointed to thetop of the beam 2. On a lateral side wall 12 of the U-shape groove 4there are mounted several stirrups 13.

FIG. 11 shows an example of pre-assembled bars 6 extending from a jointpanel zone into the U-shaped grooves 4 of the precast beams 2.

FIGS. 12 through 16 show the sequence of construction procedure. First,a column 1 is erected, a beam 2 is disposed on the top of the column(see FIGS. 12 and 13), a set of preassembled bars 6 is set in a grooveformed by the column 1 and U-shape groove 4 of the beam 2 (see FIG. 13),sleeve 3 is put in position through which a bar 5 projecting from thelower column 1 is inserted, stirrups 13 are bent over the preassembledbar 6 (see FIG. 14), the U-shape groove 4 is filled with concrete 16(see FIG. 15 a bar 5 projecting from the lower end of an upper column 1is introduced into the sleeve 3 after hardening of the concrete, and agrouting material is poured within the sleeve 3 (see FIG. 16). Theforegoing procedure is repeated until a desired number of stories areconstructed.

FIGS. l7, l8, and 19 show details of a joint panel zone. Four pairs ofbars 5 projects from a cruciform column 1 (one pair through eachflange), four beams 2 whose ends are of U-shape configuration in sectionare placed in the four directions. A set of preassembled bars 6consisting of bars 14 held in position by additional bars 15 is put inposition in the U-shape groove. Stirrups 13 are arranged around mainbars [7 of a beam which are cast in the walls of the U-shaped groove,and concrete is poured after the parts of the stirrups projecting out ofthe precast beam are bent down over the pre-assembled bars 6.

Each sleeve 3 is secured in position by connecting bars 18. Non-shrinkmortar 19 is subsequently poured within the sleeve 3. The sleeve 3 is tobe tapered towards the top and the bottom thereof and have two openingsof a minimum diameter at the ends thereof. The bars 5 are to be of adeformable type.

What we claim is:

1. A method of constructing rigid structural joints between precastconcrete columns and beams by utilizing splice sleeves of almost thesame depth as the beams, said method comprising the steps of:

a. vertically positioning a lower column having reinforcing barsextending from the upper end thereof;

b. positioning a sleeve on the lower column in such a fashion that theopposed open ends thereof align with the reinforcing bars of thecolumns;

c. inserting the reinforcing bars in the sleeve;

cl. positioning the end portion of a first beam formed with a groovewhich is U-shaped in cross section on the lower column;

e. positioning the end portion of a second beam formed with a groovewhich is U-shaped in cross section on the lower column;

f. placing a set of pre-assembled bars in the space formed by the twogrooves in the first and second beams; then g. placing an upper columnhaving reinforcing bars extending from the lower end thereof on thelower column in a fashion such that the reinforcing bars extending fromthe lower end thereof are inserted within the sleeve; then h. fillingthe interior of the sleeve with a grouting material to lock thereinforcing bars from the upper and lower columns to each other; and

i. filling the space formed by the two grooves and extending across theends of both columns with concrete in order to make the columns andbeams monolithic.

2. A method of constructing rigid structuraljoints between precastconcrete columns and beams by utilizing splice sleeves of almost thesame depth as the beams, said method comprising the steps of:

a. vertically positioning a lower column having reinforcing barsextending from the upper end thereof;

b. positioning a precast concrete block having:

i. a sleeve embedded therein with its upper and lower ends open on thesurface of the block and ii. a reinforcing bar embedded therein andextending laterally therefrom on two sides on the lower column in afashion such that the reinforcing bars of the lower column are insertedin the sleeve;

c. positioning the end portion of a first beam formed with a groovewhich is U-shaped in cross section on the lower column with thereinforcing bar embedded in the block extending into the groove;

d. positioning the end portion of a second beam formed with a groovewhich is U-shaped in cross section on the lower column with thereinforcing bar embedded in the block extending into the groove;

. placing an upper column having reinforcing bars extending from theprecast end thereof on the lower concrete block in a fashion such thatthe reinforcing bars extending from the lower end thereof are insertedwithin the sleeve; then filling the interior of the sleeve with agrouting ma- UNITED .STATES PATENT OFFICE CERTIFICATE OF CORRECTIONPATENT NO. 3,867,805 DATED February 25, 1975 INVENTOR(S) Yuzo MIKAMI eta1 It is certified that error appears in the above-identified patent andthat said Letters Patent are hereby corrected as shown below:

IN THE HEADING:

Under Foreign Application Priority Data. add the followingg May 12, 1973Japan 52731/73 Signed and sealed this 29th day of April 1975.

(SEAL) test: c MARSHALL DANN Patents RUTH C. MASON I conmxssloner ofAttesting Officer and Trademarks

1. A method of constructing rigid structural joints between precastconcrete columns and beams by utilizing splice sleeves of almost thesame depth as the beams, said method comprising the steps of: a.vertically positioning a lower column having reinforcing bars extendingfrom the upper end thereof; b. positioning a sleeve on the lower columnin such a fashion that the opposed open ends thereof align with thereinforcing bars of the columns; c. inserting the reinforcing bars inthe sleeve; d. positioning the end portion of a first beam formed with agroove which is U-shaped in cross section on the lower column; e.positioning the end portion of a second beam formed with a groove whichis U-shaped in cross section on the lower column; f. placing a set ofpre-assembled bars in the space formed by the two grooves in the firstand second beams; then g. placing an upper column having reinforcingbars extending from the lower end thereof on the lower column in afashion such that the reinforcing bars extending from the lower endthereof are inserted within the sleeve; then h. filling the interior ofthe sleeve with a grouting material to lock the reinforcing bars fromthe upper and lower columns to each other; and i. filling the spaceformed by the two grooves and extending across the ends of both columnswith concrete in order to make the columns and beams monolithic.
 2. Amethod of constructing rigid structural joints between precast concretecolumns and beams by utilizing splice sleeves of almost the same depthas the beams, said method comprising the steps of: a. verticallypositioning a lower column having reinforcing bars extending from theupper end thereof; b. positioning a precast concrete block having: i. asleeve embedded therein with its upper and lower ends open on thesurface of the block and ii. a reinforcing bar embedded therein andextending laterally therefrom on two sides on the lower column in afashion such that the reinforcing bars of the lower column are insertedin the sleeve; c. positioning the end portion of a first beam formedwith a groove which is U-shaped in cross section on the lower columnwith the reinforcing bar embedded in the block extending into thegroove; d. positioning the end portion of a second beam formed with agroove which is U-shaped in cross section on the lower column with thereinforcing bar embedded in the block extending into the groove; e.placing an upper column having reinforcing bars extending from theprecast end thereof on the lower concrete block in a fashion such thatthe reinforcing bars extending from the lower end thereof are insertedwithin the sleeve; then f. filling the interior of the sleeve with agrouting material to lock the reinforcing bars from the upper and lowercolumns to each other; and g. filling the space formed by the twogrooves and extending across the ends of both columns with concrete inorder to make the columns and beams monolithic.